1. Field of the Invention
The present invention relates to an image transfer sheet for use in (1) an electrophotographic image formation process comprising a step of electrostatically transferring a toner image to an image transfer material serving as an image receiving material such as a sheet of plain paper, using an electrophotographic copying machine, (2) a thermal image transfer recording method comprising a step of imagewise transferring a thermofusible ink or a sublimable dye, using a printer, and (3) an ink jet printing method comprising a step of imagewise transferring an aqueous ink or a thermofusible ink, using a printer. The above-mentioned electrophotographic copying machine and printers are hereinafter collectively referred to as the copying apparatus.
The present invention also relates to an image transfer sheet on which images are formed by the copying apparatus and from which the images are transferred to other image-receiving members made of, for example, cloth, canvas, plastics, paper, wood, leather, glass, earthenware and metal.
The present invention also relates to an image formation method and an image transfer method, using the above-mentioned image transfer sheet.
2. Discussion of Background
In accordance with the recent spread and development of the copying apparatus, various trials have been made so as to find new applications and uses in the copying apparatus by utilizing its various functions and capabilities other than its originally intended use for reproducing images on a sheet of plain paper.
For example, there has been proposed a new use of the copying apparatus for transferring an image formed by the copying apparatus to an image-receiving member made of a material such as cloth, leather, canvas, plastics, wood, glass, earthenware or metal, and fixing the image thereto.
The above-mentioned new use is effective for the application to the manufacturing of clothes such as T-shirts, sweat shirts, aprons and jackets, cups, trays, stained glass, panels, and reproduced pictures which are not to be made by mass-production, but made to order, or designed to be sold on a small scale. Further, such demand has greatly expanded because a full-color electrophotographic copying apparatus capable of producing high quality color images is available and high quality images can be easily printed.
As an image transfer sheet for the above-mentioned applications, there is conventionally known an image transfer sheet for the formation of a transferred image, using a toner, a thermofusible ink, a sublimable dye or an aqueous ink, as disclosed, for example, in Japanese Laid-Open Patent Application 52-82509. Furthermore, there is also known an image transfer sheet which is provided with an adhesive layer comprising a delayed-tack-type adhesive agent.
The above-mentioned image transfer sheets, however, have a problem that when image transfer is performed, at least either heat or pressure has to be applied to the image transfer sheets and therefore, it is difficult to perform image transfer to a material which is not heat resistant, such as plastics, or an article with a curved surface to which it is difficult to apply uniform pressure.
Japanese Laid-Open Patent Application 8-108610 discloses a water-pressure image transfer sheet comprising a base paper having water permeability, a releasing layer, an adhesive layer, and an image holding layer. When using this water-pressure image transfer sheet, the water-pressure image transfer sheet is immersed in water after formation of an image onto the image holding layer. The releasing layer is dissolved in water and the base paper is then peeled away from the transfer sheet. Thus, a film-like material composed of the image-bearing image holding layer and the adhesive layer is caused to float on the surface of water and then transferred to an image receiving material. Neither heat nor pressure is required for image transfer of this type of water-pressure image transfer sheet.
However, wrinkling easily occurs on the surface of the image holding layer of the conventional water-pressure image transfer sheet, as shown in a single FIGURE. Due to such wrinkling of the image holding layer, the transferred image has poor and unattractive appearance as if a film is stuck on the image receiving material. There is a demand for an image transfer sheet free of wrinkling.